1. Field of the Invention
The present invention relates to a method of using a graphical processor unit (GPU) to run Monte Carlo simulations.
2. Description of the Related Art
Graphical processor units (GPUs) are routinely included in personal computers (PCs) to improve the ability of PCs to produce high-quality display images, especially in applications such as gaming, video editing, and other processing-intensive display tasks. The architecture of the GPU is chosen for efficient coupling to the computer's video system and provides an array of special-purpose processors, termed shaders, which have been optimized for display calculations. Because the number of shaders may be large, the GPU provides a massively parallel stream processor. While first-generation graphics hardware used integer mathematics, current GPUs provide shaders that perform full 32-bit precision floating point operations.
Monte Carlo methods are stochastic techniques that are routinely used to model complex processes in which one or more steps are considered random, or quasi-random. For example, propagation of particles in scattering media can be treated as random-walks where the probability of interaction and the strength of interaction are modeled using known or presumed statistical distributions. Typically, the propagation of a given particle is traced to its conclusion, and the process is then repeated a large number of times. By recording the results for many such trials, one obtains an estimate of what outcomes are likely. Often, many trials are required in order to get good predictive power.
The field of optical in-vivo imaging utilizes light-emitting substances such as fluorescent or luminescent materials to image structures within a living organism, wherein the light-emitting substance is generated or bound or utilizes innate optical properties of the tissue, such as scatter and/or absorption, to visualize structures. Based on measurements of light made at the surface of the animal, and parameters such as the light's spatial distribution, wavelength spectrum, and signal strength, an estimate of the depth and extent of the light-emitting material, and/or of the internal structures within the organism is made. Present results obtained this way are of low quality and/or take extreme amounts of computing power (minutes or hours).